<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <script src="http://libs.baidu.com/jquery/2.0.0/jquery.js"></script>
        <script>
        $(function(){
                $('div').animate({
                    'width':'400px'
                },3000)

                $('input').click(function(){
                    $('div').stop()
                })
        })

        </script>
        <style>
div{
    width: 200px;
    height: 200px;
    background: red;
}
input{
    position: absolute;
    left: 300px;
    top: 0
}

        </style>
    </head>
    <body>
        
    <div></div>
    <input type="button" value="点击">

    </body>
</html>